':' noop results in ':: not found'

':' noop results in ':: not found'

[Tim Ruehsen]

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Hi,

maybe you can enlighten me :-)

I try to use dash (0.5.8-2.3) on Debian unstable for executing ./configure 
scripts. Since Debian builds with --disable-lineno, all ./configure scripts 
silently fall back to bash (I created bug report #842242 to get this fixed).

Next I rebuilt the package from the (Debian) sources without --disable-lineno 
and installed it. Now I see error messages from dash when it comes to the do 
nothing operator :.

$ dash -c 'test -n "a" && :'
dash: 1: :: not found
$ echo $?
127

$ bash -c 'test -n "a" && :'
$ echo $?
0

Since this : construct is wildly used and I know that dash on other systems 
work with it, I wonder what is wrong here.

Is there a known bug, maybe fixed on recent dash versions ?
Or has this some simple reason my stupidity doesn't see ?

Regards, Tim

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Re: ':' noop results in ':: not found'

[Harald van Dijk]

On 28/10/16 12:54, Tim Ruehsen wrote:
> Hi,
>
> maybe you can enlighten me :-)
>
> I try to use dash (0.5.8-2.3) on Debian unstable for executing ./configure
> scripts. Since Debian builds with --disable-lineno, all ./configure scripts
> silently fall back to bash (I created bug report #842242 to get this fixed).

As you found there, this is intentional, specifically to force configure 
scripts to continue to be run with bash, which is what happened with 
older dash versions. I asked at the time why they don't just call bash 
explicitly (bash configure instead of ./configure) if that's the goal, 
but didn't get a response.

> Next I rebuilt the package from the (Debian) sources without --disable-lineno
> and installed it. Now I see error messages from dash when it comes to the do
> nothing operator :.
>
> $ dash -c 'test -n "a" && :'
> dash: 1: :: not found
> $ echo $?
> 127
>
> $ bash -c 'test -n "a" && :'
> $ echo $?
> 0
>
> Since this : construct is wildly used and I know that dash on other systems
> work with it, I wonder what is wrong here.
>
> Is there a known bug, maybe fixed on recent dash versions ?
> Or has this some simple reason my stupidity doesn't see ?

This is likely to happen if you have the LC_ALL environment variable set 
when building dash, and I can reproduce your results with 0.5.8 by 
setting LC_ALL to en_GB.UTF-8. It was fixed in 0.5.9. (Specifically, 
where a fixed sort order was needed, 0.5.8 only forced LC_COLLATE=C, but 
that still allowed LC_ALL to override it.)

dash won't be the only program that has problems with this; if you're 
building software yourself, setting LANG should generally be okay, but 
LC_ALL is best avoided. Unless you're doing it specifically to find and 
report/fix bugs, anyway.

Cheers,
Harald van Dijk

> Regards, Tim

Re: ':' noop results in ':: not found'

[Tim Ruehsen]

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On Friday, October 28, 2016 1:22:20 PM CEST Harald van Dijk wrote:
> On 28/10/16 12:54, Tim Ruehsen wrote:
> > Hi,
> > 
> > maybe you can enlighten me :-)
> > 
> > I try to use dash (0.5.8-2.3) on Debian unstable for executing ./configure
> > scripts. Since Debian builds with --disable-lineno, all ./configure
> > scripts
> > silently fall back to bash (I created bug report #842242 to get this
> > fixed).
> As you found there, this is intentional, specifically to force configure
> scripts to continue to be run with bash, which is what happened with
> older dash versions. I asked at the time why they don't just call bash
> explicitly (bash configure instead of ./configure) if that's the goal,
> but didn't get a response.
> 
> > Next I rebuilt the package from the (Debian) sources without
> > --disable-lineno and installed it. Now I see error messages from dash
> > when it comes to the do nothing operator :.
> > 
> > $ dash -c 'test -n "a" && :'
> > dash: 1: :: not found
> > $ echo $?
> > 127
> > 
> > $ bash -c 'test -n "a" && :'
> > $ echo $?
> > 0
> > 
> > Since this : construct is wildly used and I know that dash on other
> > systems
> > work with it, I wonder what is wrong here.
> > 
> > Is there a known bug, maybe fixed on recent dash versions ?
> > Or has this some simple reason my stupidity doesn't see ?
> 
> This is likely to happen if you have the LC_ALL environment variable set
> when building dash, and I can reproduce your results with 0.5.8 by
> setting LC_ALL to en_GB.UTF-8. It was fixed in 0.5.9. (Specifically,
> where a fixed sort order was needed, 0.5.8 only forced LC_COLLATE=C, but
> that still allowed LC_ALL to override it.)

Harald !!!
That's it !
I wish you could see me grinning from ear to ear !

> dash won't be the only program that has problems with this; if you're
> building software yourself, setting LANG should generally be okay, but
> LC_ALL is best avoided. Unless you're doing it specifically to find and
> report/fix bugs, anyway.

In fact, I use LC_ALL to find bugs. Especially turkish and greek have some 
nifty casing pitfalls ;-)

Thank you so much, Harald !

Tim

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